The invention relates to a fireworks device, and especially a fireworks device wherein pyrotechnic stars are replaced by electrical/electronic light effect devices.
The invention also relates to a light effect device for use in fireworks, a fireworks system and a fireworks rocket in which the fireworks device is included.
Pyrotechnics is a field with traditions going back for many centuries. Even though technical developments have tended to produce more impressive, more precise, safer and to some extent more environmentally friendly fireworks, the basic principles are the same as in earlier times. Traditional fireworks, particularly aerial fireworks, comprise a pyrotechnic projectile which is fired into the air by means of a first charge, called the lifting charge, whereupon it is exploded by a second charge, called the booster charge. When the booster charge is fired; a number of pyrotechnic light effect devices, usually described as fireworks stars, are normally ignited and dispersed. These provide light and colours, usually creating an attractive kinetic pattern which forms the climax of the fireworks display. The timing for firing the two charges is traditionally controlled by means of a first fuse which provides the necessary time delay from lighting the fuse until firing the lifting charge, and a second fuse which provides a time delay from firing the lifting charge until firing the booster charge. In larger and more modern fireworks the first fuse has partly been replaced by electrical ignition devices.
The function of the pyrotechnic light effect devices (the stars) is to provide a relatively bright light of a given colour, colour composition or colour sequence, possibly with special extra effects, over a limited period. Normally a star of this kind consists of an internal core of glass or a metal such as lead or steel, plus one or more layers of chemical substances which on combustion provide the desired colour and effect, and on the outside an ignition layer to facilitate ignition of the star when the booster charge is fired.
In all known fireworks the star's production of light is based on combustion of a chemical substance. Such fireworks have a number of disadvantages. Amongst other things, the fireworks represent a major fire risk during use, since the falling stars burn at high temperatures and can set fire to objects on the ground or objects they meet on their way to the ground. The stars also constitute an explosion and fire risk during production, storage, transport and handling immediately preceding launching and use.
Furthermore, there is the risk that all the stars are not necessarily ignited when the booster charge is fired. This results in stars which are not ignited falling to the ground, and these objects constitute a fire and explosion risk for the future, which can be particularly dangerous in the hands of children. These undetonated remains also represent pollution of the environment, since the chemical substances in the stars can be poisonous or environmentally harmful in other ways. Correctly ignited stars also produce pollution of the area on the ground, as the star's core may contain harmful substances which are not burned, particularly when the core contains lead.
Additional problems are represented by discharges into the air during combustion of the stars. The smoke which is created during combustion is not only environmentally harmful, but is also detrimental to the visual effect of the fireworks. The formation of smoke causes the light effects from the firework and from other fireworks in the vicinity to be dimmed and obscured.
Another factor which reduces the visual effect of traditional fireworks is as follows: after the booster charge has been fired, each burning star moves in a path through the air. The motion and air resistance lead to a cooling of the star, particularly the part of the star which is located in front facing the air flow. Since the light from the star requires a high temperature, the cooling has the effect of reducing the light and thereby the visual effect of the fireworks.
The above-mentioned factors involving fire hazard and damage to the environment have resulted in the prohibition of the use of fireworks in a number of places, including city centres.
Traditional fireworks, moreover, occupy a relatively large amount of space, thus entailing high transport and storage costs.
A final problem with to-day's pyrotechnic firework stars is the risks involved in handling the chemical substances in the work environment during production of the stars.
In recent years there have been significant developments in the technology involved in electronic light sources, especially light-emitting diodes (also called light diodes or LED's). Thanks to this development, light-emitting diodes are produced to-day with substantially higher light intensity then previously. Moreover, the light-emitting diodes can be made with small dimensions, and they have a high degree of efficiency. Light-emitting diodes are therefore steadily gaining new areas of application. While light-emitting diodes were previously employed for low-level light indicators and display units, they are now being used in new fields where stringent demands are placed on visibility and intensity, for example as traffic lights, warning lights and brake lights for vehicles.
On account of the numerous drawbacks of traditional pyrotechnic stars in fireworks as mentioned above, there is clearly a need to provide fireworks, firework devices (projectiles) and light effect devices (stars) which are not encumbered by the said disadvantages, while at the same time being efficient and attractive as well as being inexpensive to produce.
There are previously known solutions which overcome some of the above-mentioned drawbacks.
U.S. Pat. No. 5,917,146 proposes reducing the problem of smoke formation which impedes the view and thereby the visual effect of the fireworks by means of a new, low-smoke chemical composition of the pyrotechnic stars.
U.S. Pat. No. 5,339,741 illustrates fireworks with reduced environmental discharge, which also provide precise firing and dispersal of firework stars. In this case the lifting charge is replaced with a compressed air-based launching device, and the projectile's booster charge is controlled by an electrical ignition device with electronic delay instead of a traditional fuse. A reduction is thereby achieved in the noise and discharge affecting the environment during launching, and great accuracy in the height calculated for the projectile when firing the booster charge. The firework stars dispersed from the projectile, however, are of the traditional, pyrotechnic type.
Flying or falling objects are also previously known, containing electronic light sources in the form of light-emitting diodes, an energy source and control/sensor devices.
U.S. Pat. No. 5,425,542 describes a flying projectile in the form of a dart, containing one or more light-emitting diodes, a battery and a switch device which is activated by relative movement between the point and the body of the dart.
U.S. Pat. No. 5,725,445 illustrates a ball containing light-emitting diodes, a flash circuit and a motion sensor.
The two above-mentioned publications have no application in the field of fireworks, and in principle are significantly different from the present invention.
U.S. Pat. No. 5,102,131 regards self-illuminated luminous playballs for nighttime play which may be either inflated or self-supporting and consist of various apparently ordinary looking balls with portable electric lighting assemblies or chemi-luminescent lights, including fireworks inside them. The playballs also comprises means for securing the illumination device inside the ball such that its centre of gravity coincides with that of the ball and on-off switching means.
A first object of the present invention is to provide a firework device which is not encumbered by the previously mentioned disadvantages.
A second object of the invention is to provide a light effect device for use in fireworks, which is not encumbered by the said disadvantages.
A third and fourth object of the invention is to provide a firework system and a firework rocket which are not encumbered by the said disadvantages.